Protect access of TCP_Server_Info::{origin,leaf}_fullpath when matching DFS connections, and get rid of TCP_Server_Info::current_fullpath while we're at it.

Cc: stable@vger.kernel.org # v6.2+ Signed-off-by: Paulo Alcantara (SUSE) pc@manguebit.com --- fs/cifs/cifsglob.h | 20 +++++++++++++------- fs/cifs/connect.c | 10 ++++++---- fs/cifs/dfs.c | 14 ++++++++------ fs/cifs/dfs.h | 13 +++++++++++-- fs/cifs/dfs_cache.c | 6 +++++- 5 files changed, 43 insertions(+), 20 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 08a73dcb7786..a62447404851 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -736,17 +736,23 @@ struct TCP_Server_Info { #endif struct mutex refpath_lock; /* protects leaf_fullpath */ /* - * Canonical DFS full paths that were used to chase referrals in mount and reconnect. + * origin_fullpath: Canonical copy of smb3_fs_context::source. + * It is used for matching existing DFS tcons. * - * origin_fullpath: first or original referral path - * leaf_fullpath: last referral path (might be changed due to nested links in reconnect) + * leaf_fullpath: Canonical DFS referral path related to this + * connection. + * It is used in DFS cache refresher, reconnect and may + * change due to nested DFS links. * - * current_fullpath: pointer to either origin_fullpath or leaf_fullpath - * NOTE: cannot be accessed outside cifs_reconnect() and smb2_reconnect() + * Both protected by @refpath_lock and @srv_lock. The @refpath_lock is + * mosly used for not requiring a copy of @leaf_fullpath when getting + * cached or new DFS referrals (which might also sleep during I/O). + * While @srv_lock is held for making string and NULL comparions against + * both fields as in mount(2) and cache refresh. * - * format: \HOST\SHARE[OPTIONAL PATH] + * format: \HOST\SHARE[\OPTIONAL PATH] */ - char *origin_fullpath, *leaf_fullpath, *current_fullpath; + char *origin_fullpath, *leaf_fullpath; };

static inline bool is_smb1(struct TCP_Server_Info *server) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index eee8b31c1eaf..340bd7cf64f3 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -454,7 +454,6 @@ static int reconnect_target_unlocked(struct TCP_Server_Info *server, struct dfs_ static int reconnect_dfs_server(struct TCP_Server_Info *server) { int rc = 0; - const char *refpath = server->current_fullpath + 1; struct dfs_cache_tgt_list tl = DFS_CACHE_TGT_LIST_INIT(tl); struct dfs_cache_tgt_iterator *target_hint = NULL; int num_targets = 0; @@ -467,8 +466,10 @@ static int reconnect_dfs_server(struct TCP_Server_Info *server) * through /proc/fs/cifs/dfscache or the target list is empty due to server settings after * refreshing the referral, so, in this case, default it to 1. */ - if (!dfs_cache_noreq_find(refpath, NULL, &tl)) + mutex_lock(&server->refpath_lock); + if (!dfs_cache_noreq_find(server->leaf_fullpath + 1, NULL, &tl)) num_targets = dfs_cache_get_nr_tgts(&tl); + mutex_unlock(&server->refpath_lock); if (!num_targets) num_targets = 1;

@@ -512,7 +513,9 @@ static int reconnect_dfs_server(struct TCP_Server_Info *server) mod_delayed_work(cifsiod_wq, &server->reconnect, 0); } while (server->tcpStatus == CifsNeedReconnect);

- dfs_cache_noreq_update_tgthint(refpath, target_hint); + mutex_lock(&server->refpath_lock); + dfs_cache_noreq_update_tgthint(server->leaf_fullpath + 1, target_hint); + mutex_unlock(&server->refpath_lock); dfs_cache_free_tgts(&tl);

/* Need to set up echo worker again once connection has been established */ @@ -1582,7 +1585,6 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx, rc = -ENOMEM; goto out_err; } - tcp_ses->current_fullpath = tcp_ses->leaf_fullpath; }

if (ctx->nosharesock) diff --git a/fs/cifs/dfs.c b/fs/cifs/dfs.c index 37f7da4f5c8b..c4ec5c67087b 100644 --- a/fs/cifs/dfs.c +++ b/fs/cifs/dfs.c @@ -248,11 +248,12 @@ static int __dfs_mount_share(struct cifs_mount_ctx *mnt_ctx) tcon = mnt_ctx->tcon;

mutex_lock(&server->refpath_lock); + spin_lock(&server->srv_lock); if (!server->origin_fullpath) { server->origin_fullpath = origin_fullpath; - server->current_fullpath = server->leaf_fullpath; origin_fullpath = NULL; } + spin_unlock(&server->srv_lock); mutex_unlock(&server->refpath_lock);

if (list_empty(&tcon->dfs_ses_list)) { @@ -342,10 +343,11 @@ static int update_server_fullpath(struct TCP_Server_Info *server, struct cifs_sb rc = PTR_ERR(npath); } else { mutex_lock(&server->refpath_lock); + spin_lock(&server->srv_lock); kfree(server->leaf_fullpath); server->leaf_fullpath = npath; + spin_unlock(&server->srv_lock); mutex_unlock(&server->refpath_lock); - server->current_fullpath = server->leaf_fullpath; } return rc; } @@ -450,7 +452,7 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t share = prefix = NULL;

/* Check if share matches with tcp ses */ - rc = dfs_cache_get_tgt_share(server->current_fullpath + 1, tit, &share, &prefix); + rc = dfs_cache_get_tgt_share(server->leaf_fullpath + 1, tit, &share, &prefix); if (rc) { cifs_dbg(VFS, "%s: failed to parse target share: %d\n", __func__, rc); break; @@ -464,7 +466,7 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t continue; }

- dfs_cache_noreq_update_tgthint(server->current_fullpath + 1, tit); + dfs_cache_noreq_update_tgthint(server->leaf_fullpath + 1, tit); tree_connect_ipc(xid, tree, cifs_sb, tcon);

scnprintf(tree, MAX_TREE_SIZE, "\%s", share); @@ -582,8 +584,8 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru cifs_sb = CIFS_SB(sb);

/* If it is not dfs or there was no cached dfs referral, then reconnect to same share */ - if (!server->current_fullpath || - dfs_cache_noreq_find(server->current_fullpath + 1, &ref, &tl)) { + if (!server->leaf_fullpath || + dfs_cache_noreq_find(server->leaf_fullpath + 1, &ref, &tl)) { rc = ops->tree_connect(xid, tcon->ses, tcon->tree_name, tcon, cifs_sb->local_nls); goto out; } diff --git a/fs/cifs/dfs.h b/fs/cifs/dfs.h index 0b8cbf721fff..1c90df5ecfbd 100644 --- a/fs/cifs/dfs.h +++ b/fs/cifs/dfs.h @@ -43,8 +43,12 @@ static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page) size_t len; char *s;

- if (unlikely(!server->origin_fullpath)) + spin_lock(&server->srv_lock); + if (unlikely(!server->origin_fullpath)) { + spin_unlock(&server->srv_lock); return ERR_PTR(-EREMOTE); + } + spin_unlock(&server->srv_lock);

s = dentry_path_raw(dentry, page, PATH_MAX); if (IS_ERR(s)) @@ -53,13 +57,18 @@ static inline char *dfs_get_automount_devname(struct dentry *dentry, void *page) if (!s[1]) s++;

+ spin_lock(&server->srv_lock); len = strlen(server->origin_fullpath); - if (s < (char *)page + len) + if (s < (char *)page + len) { + spin_unlock(&server->srv_lock); return ERR_PTR(-ENAMETOOLONG); + }

s -= len; memcpy(s, server->origin_fullpath, len); + spin_unlock(&server->srv_lock); convert_delimiter(s, '/'); + return s; }

diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c index 30cbdf8514a5..6557d7b2798a 100644 --- a/fs/cifs/dfs_cache.c +++ b/fs/cifs/dfs_cache.c @@ -1278,8 +1278,12 @@ static void refresh_cache_worker(struct work_struct *work)

spin_lock(&cifs_tcp_ses_lock); list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) { - if (!server->leaf_fullpath) + spin_lock(&server->srv_lock); + if (!server->leaf_fullpath) { + spin_unlock(&server->srv_lock); continue; + } + spin_unlock(&server->srv_lock);

list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) { if (ses->tcon_ipc) {